Device and method for reducing delay jitter in data transmission

Abstract

A delay unit 103 adds holding time that has been set by a holding time setting unit 104 to a received data. The holding time is computed based on delay time of received data and the minimum delay time of data received up to a certain point for the purpose of reducing a total delay time. The delay time is estimated in a delay time estimating unit 106 from the difference between a reception time of a packet counted based on an internal clock generator 107 and a time designated by a time stamp in the received packet.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of Invention[0002]This invention relates to a delay jitter reducing device for sequentially receiving a series of chronological data segments through a transmission path such as the Internet and delaying an individual data segment for an appropriate amount of time, thereby reducing delay jitter that has occurred in the propagation process of an individual data segment and obtaining chronological data segments from which effects of the delay jitter have been eliminated; and a delay jitter reducing method thereof.[0003]2. Description of the Related Art[0004]One form of data transmission is a real-time transmission that transmits a chronological sample of continuous signals such as, for example, voice signals after loading them to a plurality of consecutive packets. In such a real-time transmission, if delay time in transmitting a packet for individual packets are equal to one another, it is possible to obtain a voice signal of the same wavefor...

AI Technical Summary

Benefits of technology

[0030]This invention is made for solving the above-mentioned problem and aims at providing a delay jitter reducing device capable of shortening the total delay time and a delay jitter reducing method thereof.

[0032]Such a delay jitter reducing device enables the estimation of a minimum value of delay time required for transmitting data segments such as packets, thereby determining holding time of deference for reducing delay jitter based on the minimum value. As a result, delay jitter of a group of received data segments is reduced as well as the total delay time thereof is shortened.

Problems solved by technology

In a network such as the Internet, however, even in a case where a plurality of packet are transmitted from an unchanged source node to an unchanged destination node, the propagation delay time for individual packets are not necessarily the same as one another, and the propagation delay time varies among packets.

However, as described already, propagation delay time required for these individual packets to reach the receiving terminal 30 is not fixed for each voice packet.

However, the destination terminal 30 is not capable of finding how much propagation delay time it has taken for each voice packet to reach the destination.

However, in a case where the delay time of the first voice packet is as long as the maximum delay time dmax, the total delay time T results in a long period of time two times the maximum delay time dmax.

Thus, it is unfavorable that the total delay time T becomes long for the sake of reducing delay jitter.

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